From: derek_c@cix.co.uk   
      
   > *From:* Mike Swift    
   > *Date:* Wed, 15 Mar 2006 19:42:27 -0000   
   >   
   > In article <344c$4404cc44$927a2cf9$14190@FUSE.NET>,   
   >  "H2-PV NOW"  wrote:   
   >   
   > > > Wings are cheaper than fuel. Before last year's oil price gouging   
   > > > carbon-fiber fabric was down to $0.94 square foot for 6kx6k   
   > > > 2,000,000   
   > > > psi, wholesale in volume lots. The cost of 10,000 square feet of   
   > > > wings   
   > > > in material costs was less than buying a Piper Cub used. Now   
   > > > Exxon got   
   > > > their price raise and it costs a NEW Piper Cub.   
   >   
   > Comparing an air breathing winged vehicle to a VTVL all rocket   
   > vehicle the VTVL has the following advantages.  Low landing speed of   
   > about 3 mph, vs 220 mph for a winged lander.  The vehicle has about   
   > 10% less hardware (no wings or wheels).  Because there are no wings   
   > or wheels they can't fail (Shuttle). Hardware costs are in the   
   > neighborhood of $1000 per kilogram, and propellents $0.50 per   
   > kilogram.  With these numbers the break even point for cost is at 250   
   > flights per year for a vehicle designed for a ten year life, and it   
   > will be a long time before we have shuttles running that schedule.   
   > No specialized runways required to land.  In an emergency it can land   
   > on any firm level ground (DC-X).  Wings are of use only for the first   
   > two minutes of a mission, and the last one minute.  Wheels are used   
   > only the last 30 seconds of the flight.  Many engineers and managers   
   > like wings and wheels because they are a known quantity. They don't   
   > like the Buck Rogers stuff, at least until someone else does it, then   
   > it will be all the rage.   
      
   The DC-X approach still needs the mass equivalent of the wheels unless   
   you plan to use an aerospike engine and land on the plug...   
      
   As for the wings, can someone with the knowledge of the right maths do   
   some for us?   
      
   Surely the critical factor is whether the mass of extra fuel required to   
   get down safely on engine thrust is less than the mass of the wings? In   
   both cases you have to carry that mass into orbit and back again.   
      
   Obviously I'm assuming a Shuttle-like gliding approach rather than a   
   powered return for the winged vehicle.   
      
   Personally I incline towards a two-stage vehicle with the first stage   
   being winged and capable of returning to base. It may even be economic,   
   albeit somewhat dangerous, to use an air rendezvous approach on return   
   so the air-breathing first stage does the landing too and so can land   
   anywhere.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)